Project Summary Malaria is a major global health threat of which approximately 40% of the world[unreadable]s population is at risk. Approximately 1-2 million deaths can be attributed to malaria every year with an additional 300 million acute illnesses annually. Although several pharmacophores have been developed to combat malaria, quinolines are by far the most prevalent because they are chemically stable and relatively inexpensive to manufacture on a large scale, making them particularly useful for distribution in developing countries. Because of the widespread resistance to these agents, there is a pressing need to develop new antimalarial drugs against novel cellular targets within the P. falciparum parasite. Chloroquine (CQ) resistance is caused, in part, by its transport out of the digestive vacuole allowing the organism to live and propagate in the presence of high doses of the drug. The Plasmodium falciparum Chloroquine Resistance Transporter (PfCRT) has therefore been identified as attractive drug target for inhibition as well as to restore sensitivity to CQ-type drugs. The goal of this consortium is to focus on this enzyme and its mutant forms, since the wild-type protein is an essential gene product in its own right for parasite development, and because improved agents against the CQtransporting mutants would make dual therapy more effective in combination with other anti-malarial drugs. We will use a comprehensive and highly innovative strategy, encompassing high-throughput screening, drug design, in vitro and in vivo assays, medicinal chemistry, and pre-clinical testing of novel therapeutics to specifically target the essential protein PfCRT in the P. falciparum malaria parasite. We will be combining state-of-the-art chemistry design, malarial functional analysis, and high-resolution structure determination/design to discover new PfCRT inhibitors and determine their mechanisms of action, testing them also for drug metabolism/phamacokinetics. The synergy of the techniques and the combined experience of the investigators promises an exciting and effective drug development program designed to rapidly create, test, and refine novel antimalarial drugs to fight the world[unreadable]s largest killer. Our specific aims are to (1) expand the structural space for inhibitors of PfCRT, (2) optimize antimalarial activity of new agents against wild-type and chloroquine-transporting mutants of PfCRT, and (3) conduct preclinical evaluation and optimization of our PfCRT inhibitors.